How to force gcc compilator throw error when int main() have no return statement. This code compiles without any errors
#include<stdio.h>
int main(){
printf("Hi");
}
I am using
gcc -Wall -Wextra -std=c99 -Wreturn-type -Werror -pedantic-errors a.c
command for compilation
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6
This can’t be disabled, as such behavior would be in violation of the C99 standard.
Section 5.1.2.2.3 of C99 states the following regarding the main function:
If the return type of the
mainfunction is a type compatible withint,
a return from the initial call to the main function is equivalent to
calling theexitfunction with the value returned by themainfunction
as its argument; reaching the}that terminates themainfunction
returns a value of 0. If the return type is not compatible withint,
the termination status returned to the host environment is
unspecified.
You can avoid the special treatment that main receives by renaming it. Compiling with -Dmain=AlternateName -Werror=return-type yields “error: control reaches end of non-void function”.
Naturally, you would do this as a special compilation to test for the issue and not use the object module resulting from this compilation. A second normal compilation without -Dmain=AlternateName would be used to generate the object module.
It is not possible as it correct in C99
5.1.2.2.3 Program termination 1 If the return type of the main function is a type compatible with int, a return from the initial call
to the main function is equivalent to calling the exit function with
the value returned by the main function as its argument; 11) reaching
the } that terminates the main function returns a value of 0. If the
return type is not compatible with int, the termination status
returned to the host environment is unspecified.
2